BlueZ to move to standard D-Bus interfaces

During the last week I was in Recife, Brazil, together with Henrique Dante, Ulisses Furquim and other fellows attending the BlueZ meeting. We discussed several topics, among them the upcoming BlueZ 5 API. That discussion started by Johan and Marcel saying BlueZ would not move to DBus.Properties and DBus.ObjectManager anymore for the next version. Main reason being that BlueZ now will have more frequent releases than it had in past and therefore there wasn’t enough time to convert the API. However I and Luiz von Dentz already had an almost working solution: I implemented DBus.Properties and he did the DBus.ObjectManager, so we received the news with much regret.

Since these changes break the API, not accepting them now means we’d need to wait for BlueZ 6 in order to have these interfaces, which expected to happen only on later next year. Thus we argued that and Marcel Holtmann challenged us to make a demo on Wednesday. Challenge accepted! After working one night to put the implementations together and finish the DBus.PropertiesChanged signal we could present such a demo. And it worked without any issues. To say the truth we only converted 2 interfaces (Adapter and Manager), but that was enough to convince them we can finish this in time for BlueZ 5.0. Or at least that’s what we hope. Final consensus: this change is back on track for the upcoming major release of BlueZ.

Now we are polishing the implementation and start sending the patches. The first patch set was already sent and hopefully soon all the others will reach BlueZ’s mailing list.

So, why is this important? By implementing these interfaces, that are part of the D-Bus specification, it becomes much easier to write client code to talk to bluetoothd and since D-Bus bindings already have implementations for them it’s much less error prone, too. At the same time we are aiming to simplify the code needed in bluetoothd to support our use-cases, so for both people who write bluetoothd and for those who write client applications this will be beneficial.